411 Matching Results

Search Results

Advanced search parameters have been applied.

Hydraulic Activity in Synthetic and Commercial Slags

Description: Slag, by itself, shows very little hydraulic activity. However, hydration is greatly accelerated by incorporation of the slag with Portland cement. This phenomenon is due to the activating role of calcium hydroxide released from the hydration of Portland cement. This study was aimed at finding other activators that will increase hydration in both synthetic and commercial slags. The effects of chemical composition and the aggregation state of the slag on the hydration process were also investigated. For the synthetic slags, the aggregation state was altered by different quenching techniques. The chemical composition was varied by synthesizing a series of slags. The degree of hydration was studied by developing a thermogravimetric analysis technique and the glass content was determined using microscopy. Minerals were determined using powder x-ray diffraction analysis.
Date: May 1982
Creator: Saad, Bahruddin bin
Partner: UNT Libraries

Investigation of the Potential Hazard in Releasing Scrap Steel Contaminated with Uranium to Commercial Channels

Description: Tests were conducted on a laboratory and semi-plant scale to determine the effect of permitting scrap grossly contaminated with uranium to be used in steel manufacture. It was found the most of the uranium is removed with the slag. Steel made with this scrap would have a uranium constituent so little above that made with uncontaminated scrap as to be hardly significant. The slag itself would not present any hazard in handling or normal use. It is recommended, therefore, that in the future steel with only surface uranium contamination be released through normal scrap channels.
Date: June 15, 1951
Creator: Blatz, Hanson; Harley, John H. & Eisenbud, Merril
Partner: UNT Libraries Government Documents Department

Slag Characterization and Removal Using Pulse Detonation Technology During Coal Gasification

Description: The main activity in the first quarter of 1998 was concentrated on understanding the detonation code, so that it can be linked with the in-house CFD code NPARC for simulation. The objective is to obtain the velocity and pressure distribution inside the detonation tube and compare with the experimental data that we have obtained from the experiments. Once the code is validated, the simulation will be extended to obtain the pressure and velocity fields in the large chamber, i.e., outside the exit of the detonation tube where the slag samples are attached.
Date: April 30, 1998
Creator: Mei, Daniel; Zhou, Jianren; Biney, Paul O. & Huque, Ziaul
Partner: UNT Libraries Government Documents Department

Canyon dissolution of sand, slag, and crucible residues

Description: An alternative to the FB-Line scrap recovery dissolver was desired for the dissolution of sand, slag, and crucible (SS{ampersand}C) residues from the plutonium reduction process due to the potential generation of hydrogen gas concentrations above the lower flammability limit. To address this concern, a flowsheet was developed for the F-Canyon dissolvers. The dissolvers are continually purged with nominally 33 SCFM of air; therefore the generation of flammable gas concentrations should not be a concern. Following removal of crucible fragments, small batches of the remaining sand fines or slag chunks containing less than approximately 350 grams of plutonium can be dissolved using the center insert in each of the four annular dissolver ports to address nuclear criticality safety concerns. Complete dissolution of the sand fines and slag chunks was achieved in laboratory experiments by heating between 75 and 85 degrees Celsius in a 9.3M nitric acid/0.013M (hydrogen) fluoride solution. Under these conditions, the sand and slag samples dissolved between 1 and 3 hours. Complete dissolution of plutonium and calcium fluorides in the slag required adjusting the dissolver solution to 7.5 wt% aluminum nitrate nonahydrate (ANN). Once ANN was added to a dissolver solution, further dissolution of any plutonium oxide (PuO2) in successive charges was not practical due to complexation of the fluoride by aluminum. During the laboratory experiments, well mixed solutions were necessary to achieve rapid dissolution rates. When agitation was not provided, sand fines dissolved very slowly. Measurement of the hydrogen gas generation rate during dissolution of slag samples was used to estimate the amount of metal in the chunks. Depending upon the yield of the reduction, the values ranged between approximately 1 (good yield) and 20% (poor yield). Aging of the slag will reduce the potential for hydrogen generation as calcium metal oxidizes over time. The potential for excessive ...
Date: December 1, 1997
Creator: Rudisill, T.S.; Gray, J.H.; Karraker, D.G. & Chandler, G.T.
Partner: UNT Libraries Government Documents Department

Slag characterization and removal using pulse detonation for coal gasification

Description: This report is a preliminary economic analysis of the Sherburne Co. plant North State Power. This analysis is made with the cooperation of Joe Brojberg (senior analysis engineer of NSP) and Steve Bension (Slag and ash specialist, President of Microbeam Technologies Incorporated (MTI) of North Dakota) and Paul Johnson of Diamond Power Speciality.
Date: June 25, 1997
Creator: Huque, Z.; Mei, D.; Biney, P.O. & Zhou, J.
Partner: UNT Libraries Government Documents Department

CSER 96-013: Cementation Process, glovebox HA-20MB at PFP

Description: This evaluation provides criticality safety controls for the cementation processing in Glovebox HA-2OMB at the Plutonium Finishing Plant. Slag and crucible residues from Pu button making will be blended with Portland cement in 5k-in. diam. x 7-in. tall cans, for eventual disposition in special DOT 17C drums. A maximum of 180 g Pu is allowed per liquid-bearing container (mixing bowl, filter funnel, or cement can). In this SD revision, three separate areas with 500 g Pu limits each are established; the airlock cell for input S&C cans, the reaction- and mixing-process area, and a cemented-can storage area. Number and spacing of containers within an area is not restricted, for areas spaced 6 inches apart. Acid addition in the reaction stage is allowed to the extent that plutonium dissolution will not occur.
Date: September 1, 1996
Creator: Hess, A.L.
Partner: UNT Libraries Government Documents Department

Flowsheet modifications for dissolution of sand, slag, and crucible residues in the F-canyon dissolvers

Description: An initial flowsheet for the dissolution of sand, slag, and crucible (SS{ampersand}C) was developed for the F- Canyon dissolvers as an alternative to dissolution in FB-Line. In that flowsheet, the sand fines were separated from the slag chunks and crucible fragments. Those two SS{ampersand}C streams were packaged separately in mild-steel cans for dissolution in the 6.4D dissolver. Nuclear safety constraints limited the dissolver charge to approximately 350 grams of plutonium in two of the three wells of the dissolver insert and required 0.23M (molar) boron as a soluble neutron poison in the 9.3M nitric acid/0.013M fluoride dissolver solution. During the first dissolution of SS{ampersand}C fines, it became apparent that a significant amount of the plutonium charged to the 6.4D dissolver did not dissolve in the time predicted by previous laboratory experiments. The extended dissolution time was attributed to fluoride complexation by boron. An extensive research and development (R{ampersand}D) program was initiated to investigate the dissolution chemistry and the physical configuration of the dissolver insert to understand what flowsheet modifications were needed to achieve a viable dissolution process.
Date: December 1, 1997
Creator: Rudisill, T.S.; Karraker, D.G. & Graham, F.R.
Partner: UNT Libraries Government Documents Department

Nonequilibrium Sulfur Capture & Retention in an Air Cooled Slagging Coal Combustor

Description: Calcium oxide injected in a slagging combustor reacts with the sulfur from coal combustion to form sulfur-bearing particles, which are deposited on the liquid slag layer on the combustor wall. Due to the low solubility of sulfur in slag, it must be rapidly drained from the combustor to limit sulfur gas re-evolution. Analysis indicated that slag mass flow rates in excess of 400 lb/hr should limit sulfur re-evolution. The objective of this 36 month project was to perform a series of tests to determine the factors that control the retention of the sulfur in the slag. 19 days of testing were completed prior to 9/30/97. In the present quarterly reporting period ending 12/31/97, 13 tests days were completed on co-firing coal and a high ash, rice husk biomass, which was selected to produce a high slag flow rate. Most of the test effort focussed on developing methods for feeding the very low density rice husks into combustor. Various levels of mineral matter from coal ash, rice husk ash, calcium sulfate, and calcium oxide was injected in the combustor during these 13 tests. The peak mineral matter, injection rate was 592 lb/hr for a period of about one-hour. No significant sulfur concentration was measured in the slag removed from the combustor. This may be due to the brief test duration, and longer duration tests are planned for the next quarter. The two major accomplishments in this quarter are the successful co-firing of coal and biomass in the slagging combustor. This is a major technical milestone due to its application to greenhouse gas emission reduction. It was not in the original project plan. Also, the total of 31 test days completed by 12/31/97 is double the number originally planned.
Date: April 21, 1998
Creator: Zauderer, Bert
Partner: UNT Libraries Government Documents Department

Task 6.7.2 - Improved Corrosion Resistance of Alumina Refractories

Description: In order to increase the efficiency of advanced coal-fired power systems, higher working, fluid temperatures must be reached. To protect some system surfaces, they are covered with corrosion-resistant refractories. Corrosion is the degradation of material surfaces or grain boundaries by chemical reactions with melts, liquids, or gases, causing loss of material and, consequently, a decrease in strength of the structure. In order to develop methods of reducing corrosion, the microstructure that is attacked must be identified along with the mechanism and rates of the attack. Once identified, methods for reducing corrosion rates can be developed. In order to determine the reactivity of a refractory to a slag, several tests have been developed. The most common are the cup slag test, drip slag test American Society for Testing and Materials ([ASTM] C768), gradient slag test, rotary slag test (ASTM C874)and the dip-and- spin test. Among these tests, the cup slag test is the only static test method and the most commonly used. Previous static testing at the University of North Dakota Energy & Environmental Research Center (EERC) has shown that alumina-based castable refractories are among the least expensive and most corrosion-resistant materials for the highest-temperature coal-fired power system applications.
Date: February 1, 1998
Creator: Hurley, John P. & Kleven, Patricia L.
Partner: UNT Libraries Government Documents Department

Production of Uranium Metal

Description: Experiments were carried out for the purpose of increasing production, efficiency, and purity of uranium metal. The electrolytic method as described by Driggs and Lilliendahl for the preparation of uranium metal was followed with but little deviation. The yield of metal at the very best was only 50%. The metal powder produced, at times, was very pyrophoric. Methods were found whereby the metal, at least in part, can be made from the oxides with an average yield of about 90%. The small amounts of sludge and slag accumulated in this modified process can readily be re-used in the electrolysis pot and, therefore, an overall yield of 96% can be obtained. Information accumulated from these experiments has been compiled in such a manner as to be readily available for factory use, for patent purposes and for future publication.
Date: February 17, 1943
Creator: Nagy, R.
Partner: UNT Libraries Government Documents Department

CERIUM AND PLUTONIUM DIOXIDE--NOTES ON REDUCTION TO MASSIVE METAL

Description: In reduction reactions of CeO/sub 2/, with calcium and a CaCl/sub 2/ flux, the use of vibrational energy was shown to have a marked effect on the yield of coalesced metal. Buttons of 40 to 50% theoretical yield were obtained from the vibrated reductions. As the flux concentration is decreased, the slag becomes more viscous containing undissolved CaO. The undissolved CaO present prevents the metal from completely coalescing, but the metal can be recovered from the slag and coalesced under CaCl/sub 2/ containing a small amount of calcium to reduce any oxide skin present. Cerium pellet yields of 50 to 60% metal were obtained by the procedure and were not difficult to handle in air. Cerium was used as a stand-in material for plutonium. (B.O.G.)
Date: February 13, 1956
Creator: Tolley, W. B.
Partner: UNT Libraries Government Documents Department

Reduction of Oxidative Melt Loss of Aluminum and Its Alloys

Description: This project led to an improved understanding of the mechanisms of dross formation. The microstructural evolution in industrial dross samples was determined. Results suggested that dross that forms in layers with structure and composition determined by the local magnesium concentration alone. This finding is supported by fundamental studies of molten metal surfaces. X-ray photoelectron spectroscopy data revealed that only magnesium segregates to the molten aluminum alloy surface and reacts to form a growing oxide layer. X-ray diffraction techniques that were using to investigate an oxidizing molten aluminum alloy surface confirmed for the first time that magnesium oxide is the initial crystalline phase that forms during metal oxidation. The analytical techniques developed in this project are now available to investigate other molten metal surfaces. Based on the improved understanding of dross initiation, formation and growth, technology was developed to minimize melt loss. The concept is based on covering the molten metal surface with a reusable physical barrier. Tests in a laboratory-scale reverberatory furnace confirmed the results of bench-scale tests. The main highlights of the work done include: A clear understanding of the kinetics of dross formation and the effect of different alloying elements on dross formation was obtained. It was determined that the dross evolves in similar ways regardless of the aluminum alloy being melted and the results showed that amorphous aluminum nitride forms first, followed by amorphous magnesium oxide and crystalline magnesium oxide in all alloys that contain magnesium. Evaluation of the molten aluminum alloy surface during melting and holding indicated that magnesium oxide is the first crystalline phase to form during oxidation of a clean aluminum alloy surface. Based on dross evaluation and melt tests it became clear that the major contributing factor to aluminum alloy dross was in the alloys with Mg content. Mg was identified as the ...
Date: March 17, 2006
Creator: Das, Dr. Subodh K. & Ningileri, Shridas
Partner: UNT Libraries Government Documents Department

A ceramographic evaluation of chromia refractories corroded by slag

Description: This paper describes the ceramographic preparation of Cr{sub 2}O{sub 3}-Al{sub 2}O{sub 3} refractory bricks and subsequent microstructural analysis to determine the corrosive effects of molten slag. The porous and friable nature of the brick, especially after exposure to the slag or its individual components, presented some problems in the preparation.
Date: January 1, 2001
Creator: Hunt, Alton H. & Chinn, Richard E.
Partner: UNT Libraries Government Documents Department